WASHINGTON (AP) - The FBI thought it was closing in on Joran van der Sloot in the notorious Natalee Holloway missing-teenager case, and he was videotaped and paid $25,000 in a sting operation. But when the agency delayed his arrest to help build a criminal case, he took the money and headed for Peru, where authorities say he now has confessed to killing a different young woman.

The investigation of Van der Sloot in the Alabama teenager's case simply was not far enough along to have him arrested, the FBI and the U.S. attorney's office in Birmingham said Wednesday.

Holloway disappeared on the island of Aruba on May 30, 2005.

Van der Sloot is now expected to be charged with murder in Peru in the killing, exactly five years later, of 21-year-old business student Stephany Flores, the daughter of a Peruvian circus promoter and former race car driver whom he meet playing poker at a casino.

In his hotel room, Van der Sloot strangled Flores with his two hands and smashed her in the face with an elbow, the chief of Peru's criminal police, Gen. Cesar Guardia, told The Associated Press in Lima on Wednesday.

"He's irascible. He has no self-control," Guardia said. He's also very calculated, the general said, taking Flores' cash, about $300 in Peruvian currency, and two credit cards.

The 22-year-old Dutchman's confession was so thorough - and backed by such conclusive evidence - that police decided to waive the usual crime scene visit, Guardia added.

Police will formally ask prosecutors Thursday to charge Van der Sloot with murder, for which he would face from 15 to 35 years in prison if convicted.

Guardia said Van der Sloot attested in his confession Monday that he killed Flores because she found out about the Aruba case by using his laptop without his permission. But he said police didn't necessarily believe him.

The evidence against the Dutchman includes hotel security camera video showing Flores and Van der Sloot entering his hotel room together and the Dutchman leaving alone four hours later.

U.S. law enforcement officials and a private investigator said the work on Holloway's disappearance was revived in April when Van der Sloot reached out to a lawyer for Holloway's mother and requested $250,000 in exchange for disclosing the location of the young woman's body on the island of Aruba.